Of course you want to look at http://www.w3.org/TR/1998/REC-CSS2-19980512/, but before you do that take a look at some of these other sites and see how they do it on a real page:
css.maxdesign.com.au/
http://www.stopdesign.com/articles/design_process/
http://www.thenoodleincident.com/index.html
www.w3schools.com
Basically what you will find by reading these is that you start by placing your bare content in the page. For example, your page might look something like:
code:
<h1>Page Title</h1>
<h2>Sub Title</h2>
<p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam</p>
<h2>Sub Title</h2>
<p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam</p>
Just get the structure of the page laid out in terms of the individual types of elements.
This will allow the page to degrade gracefully in browsers that don't support css.
Once I have that complete, I start adding css and testing in Firefox. I use Firefox because it's compliant with w3c. You might want to use opera or another browser, but don't use Internet Explorer first.
Your first css test should be in the most standards compliant browser you can find.
After you get the page looking like you want, validate the HTML at http://validator.w3.org/, then validate the CSS at [url]http://jigsaw.w3.org/css-validator/[/utl]. Keep in mind that the validators are your friends. They will often help you find places in your page that are causing the page not to display properly. So if you get to a point where you are having difficulty getting something to work properly, try validating it.
Now you are ready to start getting the page to work in Internet Explorer. This all becomes an iterative process where you get the page to work in Firefox, validate it, get it to work in Internet Explorer and go back and test it in Firefox, etc.
.
-- not necessarily stoned... just beautiful.